This invention relates to a method of, and apparatus for, manufacturing metal strip in which the metal strip is cast in a roll caster.
It is known from JP-A-56-119607 for a metal slab to be cast in a continuous casting mould and for the slab to be hot rolled in a rolling mill train to metal strip which is subsequently coiled in coils of a convenient size. It is also known from the same Japanese specification for a metal workpiece to be cast in a roller caster and continuously conveyed through a looper into a heating furnace where its temperature is raised to a rolling temperature subsequent to the workpiece being rolled down to strip in a rolling mill train. The speed of casting and the rolling speed in the in-line rolling mill train have to be synchronised and the looper present at the inlet end of the heating furnace is used to take up any differences in these speeds. Pinch roll assemblies are provided between the outlet of the roll caster and the looper so that, in use, the looped workpiece is present between the pinch roll assemblies and the entrance to the heating furnace.
However, if the metal strip is cast to substantially the required thickness in the roll caster and is not subsequently subjected to rolling in an in-line rolling mill train, then following the caster the strip passes through a temperature control zone where the temperature of the strip is controlled. On leaving the temperature control zone, the temperature of the strip has to be within a band close to a predetermined temperature in order to achieve the required material condition and properties. During the start up of the casting process, the speed of the strip can vary dramatically whilst the strip temperature leaving the caster is relatively close to its steady casting temperature, hence, the strip temperature in the temperature control zone will also vary until steady state casting speed is achieved.